Current automatic meter reading (AMR) systems include, as one of the major components of the system, a large number of endpoints, each endpoint being comprised of an ERT® (encoder, receiver, transmitter) that is interfaced to a utility meter. In a typical system, the ERT® obtains a consumption reading from the utility meter, such as consumption of water, gas, or electricity. A conventional endpoint which includes a communicator, such as a radio transceiver, transmits the consumption information to an intermediate receiver device according to the AMR system paradigm. In some endpoint applications, battery power is preferred. For example, gas or water meters that are battery-powered do not need to be connected to, and reliant upon, line power. Even electricity consumption meters, which are by their nature connected to the line power, can benefit from an independent power source. An independently-powered endpoint can inform the central utility about any occurrence of power outage or unauthorized tampering.
Battery-powered endpoints have been designed to limit the power consumed in day-to-day operation. One well-known design feature is a bubble-up mode of operation, in which an endpoint “bubbles-up,” or activates its transceiver to communicate or attempt to communicate with the AMR data collection system, according to a preset schedule. The time duration or period between bubble-up events may typically span seconds or minutes.
Some AMR systems have a fixed, or installed, meter reading infrastructure that listens for transmissions from utility meter endpoints occurring on a bubble-up basis. In other systems, a typical endpoint bubbles up at a pre-set time to activate its receiver circuitry, which becomes receptive to a signal from an intermediate receiver or the like that prompts the endpoint to send the consumption reading to the reader or receiver. Some AMR systems utilize portable or vehicle-mounted reading devices that are transported along a meter reading route by utility personnel. A meter reading route is generally planned to pass within communications proximity to the utility meters to be read. Some AMR systems use a combination of fixed and mobile meter reading devices where, for example, the fixed devices communicate with endpoints at regular scheduled intervals, and the mobile devices communicate with selected endpoints on an as-needed basis.
Utility meters are generally read on periodic intervals, such as hourly, daily, weekly, monthly, etc. The meter reads may occur at regularly spaced, pre-determined times in each period such as, for example, on the first day of each month. A challenge for systems designers is accommodating a common practice among utilities to vary the meter reading frequency of each occurrence. Variations may be due to factors such as scheduling changes, migration to different AMR systems, work backlogs, downtime, and the like. For example, a utility may ordinarily request information from a given meter on a semi-monthly basis during one portion of the year, and on a weekly basis during another portion of the year. It is also common practice among utilities to take readings from utility meters, and return to a particular area shortly thereafter to request additional data or repeated data from certain utility meters. Therefore, actual communication between meter and reader does not necessarily take place on a consistent schedule.
A short bubble up cycle (a high bubble-up frequency) can improve system performance by creating a greater likelihood of achieving communications between a utility meter endpoint and a receiver (or reader). In a situation in which a mobile reader follows a route that passes near a given meter, there exists a narrow window of opportunity for the meter endpoint to successfully interface with the reading device during the time that the reader is within communications proximity to the meter. Therefore, one challenge associated with bubble-up operation is pre-setting a frequency for bubble-up events. System designers must trade off system communications reliability, which is improved with more frequent bubble-ups, against battery-powered endpoint energy consumption, which is improved with less frequent bubble-ups.